While the treatment of cancer was once considered impossible, great strides have been made during the past ten years in controlling the ravages of this often fatal disease. Several drugs which contribute to the increasing rate of survival are now routinely used clinically. The most commonly employed antitumor agents include methotrexate, doxorubicin and the vinca alkaloids such as vincristine. However, research continues to develop more effective compounds with greater safety for subjects under treatment. This invention provides an additional method of treating tumors.